When computers interpret natural language, selecting the correct interpretation for each word in the expression is very important. An introduction to the disambiguation and reference resolution art can be found from:    Marjorie McShane: Reference Resolution Challenges for an Intelligent Agent: The Need for Knowledge, IEEE Intelligent Systems, 24(4):47-58, July/August 2009    R. Navigli: Word Sense Disambiguation: A Survey, Computing Surveys, 41(2), pp. 10:1-10:69, February 2009.    An overview of knowledge representation methods can be found in R. Brachman et al: Knowledge Representation and Reasoning, Elsevier, 2004. Detailed treatments of semantic networks can be found in J. F. Sowa: Conceptual Structures: Information Processing in Mind and Machine, Addison-Wesley, 1984; J. F. Sowa: Principles of Semantic Networks: Explorations in the Representation of Knowledge, Morgan Kaufmann, 1991; and H. Helbig: Knowledge Representation and the Semantics of Natural Language, Springer, 2006.
All of the above mentioned references are hereby incorporated herein by reference in their entirety.
Despite extensive research, natural language parsing systems still have many shortcomings in disambiguation and reference resolution, as illustrated by McShane (2009).